Frozen aerated confections, such as ice creams, sorbets and the like are popular foodstuffs. Typically they are aerated to an overrun of about 100%. Fat is an important constituent of such confections. Conventionally, frozen aerated confections have been prepared with fats having a high proportion of saturated fat, for example dairy fat (60-65%) or coconut oil (90%), together with emulsifiers such as mono/di-glycerides of fatty acids. Typically the emulsifiers are present at about 0.1% by weight of the confection. Saturated fats are conventionally used because they are mostly solid at the temperatures at which freezing and aeration take place in an ice cream freezer. The presence of solid fat together with an emulsifier results in ice cream that can be aerated uniformly and consistently, holds its shape after extrusion and has a good texture when eaten (see for example, “Ice Cream”, 6th Edition R. T. Marshall, H. D. Goff and R. W. Hartel, Kluwer Academic/Plenum Publishers, New York 2003, pages 36, 42-43 and 69; or “The Science of Ice Cream”, C. Clarke, Royal Society of Chemistry, Cambridge, 2004, pages 46-48 and 62-73). Shape formation and retention is a critical factor in producing products which are shaped on extrusion, for example Viennetta™. Such products cannot normally be produced with a low level of solid fat, because liquid fat produces an unstable air phase resulting in uneven aeration and poor shaping properties.
Health-conscious consumers are now looking for frozen aerated confections which have all the properties of these traditional products but which are healthier. It has therefore been proposed to produce frozen aerated confections in which saturated fats are replaced by mono- or polyunsaturated fats. U.S. Pat. No. 5,478,587 discloses compositions useful for preparing frozen desserts based on a non-dairy creamer containing canola (rapeseed) oil and mono-/di-glycerides. Although the composition is said to be useful for preparing frozen desserts, none are exemplified. It has not been possible simply to replace the saturated fats in ice cream formulations with unsaturated fats (which are liquid at ambient temperatures) and obtain the desired shaping properties and consistency of aeration, because unsaturated fats do not contain sufficient solid fat. Thus there remains a need to provide frozen aerated confections containing low levels of saturated fats which have good aeration and shaping properties.